package day07;

import java.util.Random;

public class VerificationCode {
    public static void main(String[] args) {
        String arr = generateVeriCode(4);
        System.out.println(arr);

    }
    public static String generateVeriCode(int len){
        String code = "";
        char[] chs = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p',
                'q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G',
                'H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X',
                'Y','Z','1','2','3','4','5','6','7','8','9'};
        Random rand = new Random();
       for (int i =1; i <=len ; i++) {
           int index = rand.nextInt(chs.length);
           //int index = (int)(Math.random()* chs.length);
            code += chs[index];
        }
        return code;
    }
}
